1. Field of the Invention
This invention relates to ink recording equipment and more particularly to a pressure roller bar for such equipment.
2. Prior Art
Pressure rollers used for pressing a data carrier, such as a sheet of paper, against the platen of a teleprinter or data printer or other ink recording device, are known wherein the pressure rollers are mounted on a hinged pivotable clamp bar, which may be spring biased against the platen. The clamp bar is normally positioned behind the printing position in the direction of feed flow of the paper.
In that type of ink recording device where the recording fluid is applied to the paper in a drop-like form from a recording head such as a jet ink recorder, special inks are used. Normally the inks are chosen such that they do not air dry so that they strike the recording carrier in a liquid state. In order to insure this, hygroscopic additives are provided which supplement those components of the recording fluid or ink which would otherwise evaporate due to air absorption.
Recording fluids of this type are designed to become smear resistant on the recording carrier or paper by penetration into the fibers of the paper. This penetration is dependent upon the suction or absorption capability of the paper and complete penetration may take upwardly of one second. During the time period from droplet deposit on the paper to full absorption the printing can be smeared.
It has been known in ink recording devices to use hinge clamps which are equipped with pressure rollers which press the paper against the platen. Such pressure rollers have generally been constructed of rubber. Although clamps of this type, and their associated pressure rollers, are generally positioned at such a distance from the print position that the ink will be smear resistant by the time it comes into contact with the pressure rollers during normal printing operations, it is possible for smearing to occur if, for example, a continuous line feed is actuated immediately following the application of the last print character. In such instances, it is possible that recording fluid will not yet have been fully absorbed into the paper by the time the paper, under the influence of the continuous line feed, is advanced past the pressure rollers. In such an instance the rollers will pick up some of the ink and return it to the paper on the next revolution of the pressure roller.
It would therefore be an advance in the art to provide a pressure roller which would not take up unabsorbed ink and return it to the recording carrier at a different position.